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| author |   Yufen Yu <yuyufen@huawei.com> | 2018-02-24 12:05:56 +0800 |
|---|---|---|
| committer |   Shaohua Li <sh.li@alibaba-inc.com> | 2018-02-25 10:44:39 -0800 |
| commit | 3de59bb9d551428cbdc76a9ea57883f82e350b4d (patch) | |
| tree | e52cf39c6f24c60dca270845a5163c37fa8f2009 /drivers/md | |
| parent | md: fix a potential deadlock of raid5/raid10 reshape (diff) | |
| download | linux-dev-3de59bb9d551428cbdc76a9ea57883f82e350b4d.tar.xz linux-dev-3de59bb9d551428cbdc76a9ea57883f82e350b4d.zip | |
md/raid1: fix NULL pointer dereference
In handle_write_finished(), if r1_bio->bios[m] != NULL, it thinks
the corresponding conf->mirrors[m].rdev is also not NULL. But, it
is not always true.
Even if some io hold replacement rdev(i.e. rdev->nr_pending.count > 0),
raid1_remove_disk() can also set the rdev as NULL. That means,
bios[m] != NULL, but mirrors[m].rdev is NULL, resulting in NULL
pointer dereference in handle_write_finished and sync_request_write.
This patch can fix BUGs as follows:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000140
IP: [<ffffffff815bbbbd>] raid1d+0x2bd/0xfc0
PGD 12ab52067 PUD 12f587067 PMD 0
Oops: 0000 [#1] SMP
CPU: 1 PID: 2008 Comm: md3_raid1 Not tainted 4.1.44+ #130
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1.fc26 04/01/2014
Call Trace:
? schedule+0x37/0x90
? prepare_to_wait_event+0x83/0xf0
md_thread+0x144/0x150
? wake_atomic_t_function+0x70/0x70
? md_start_sync+0xf0/0xf0
kthread+0xd8/0xf0
? kthread_worker_fn+0x160/0x160
ret_from_fork+0x42/0x70
? kthread_worker_fn+0x160/0x160
BUG: unable to handle kernel NULL pointer dereference at 00000000000000b8
IP: sync_request_write+0x9e/0x980
PGD 800000007c518067 P4D 800000007c518067 PUD 8002b067 PMD 0
Oops: 0000 [#1] SMP PTI
CPU: 24 PID: 2549 Comm: md3_raid1 Not tainted 4.15.0+ #118
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1.fc26 04/01/2014
Call Trace:
? sched_clock+0x5/0x10
? sched_clock_cpu+0xc/0xb0
? flush_pending_writes+0x3a/0xd0
? pick_next_task_fair+0x4d5/0x5f0
? __switch_to+0xa2/0x430
raid1d+0x65a/0x870
? find_pers+0x70/0x70
? find_pers+0x70/0x70
? md_thread+0x11c/0x160
md_thread+0x11c/0x160
? finish_wait+0x80/0x80
kthread+0x111/0x130
? kthread_create_worker_on_cpu+0x70/0x70
? do_syscall_64+0x6f/0x190
? SyS_exit_group+0x10/0x10
ret_from_fork+0x35/0x40
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: Yufen Yu <yuyufen@huawei.com>
Signed-off-by: Shaohua Li <sh.li@alibaba-inc.com>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/raid1.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index f978eddc7a21..fe872dc6712e 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -1809,6 +1809,17 @@ static int raid1_remove_disk(struct mddev *mddev, struct md_rdev *rdev) struct md_rdev *repl = conf->mirrors[conf->raid_disks + number].rdev; freeze_array(conf, 0); + if (atomic_read(&repl->nr_pending)) { + /* It means that some queued IO of retry_list + * hold repl. Thus, we cannot set replacement + * as NULL, avoiding rdev NULL pointer + * dereference in sync_request_write and + * handle_write_finished. + */ + err = -EBUSY; + unfreeze_array(conf); + goto abort; + } clear_bit(Replacement, &repl->flags); p->rdev = repl; conf->mirrors[conf->raid_disks + number].rdev = NULL; |